Conventionally, image processing is known as screen image transfer methods of transferring, to another device (e.g. a recording server), the content on the screen of the display of the personal computer (PC) that is changed over time due to use, for example, in real time. In order to avoid an increase in data volumes due to transfer of image data in the bitmap format, the image processing includes reducing resolution, reducing gray scale level of colors, and roughening pictures by transferring image data that is converted into JPEG format, by transferring only differences, or by transferring differences that are converted into JPEG format (e.g. see JP 2009-10871 A).